On the twentieth day, the crisis entered a new phase.
The spatial overlap phenomenon in Berlin had expanded from isolated buildings to entire city blocks. People walking down the street would suddenly catch sight of buildings as they had stood before being destroyed in 1945, see phantom-like figures in period attire, even hear the bells of pre-war trams ringing in the air.
Even more bizarrely, some people were beginning to "sync up" with these overlapping scenes. An elderly man living in modern-day Berlin discovered that his mirror human counterpart was a child who had died in the 1945 bombing. When the two met, the child's ghostly form began to take on physical substance, while the elderly man started to fade into transparency.
This wasn't an isolated case. Similar instances of "physical exchange" were being reported all over the world.
The United Nations issued the highest level of alert, advising all mirror humans to avoid contact with their counterparts. But it was already too late. Spontaneously organized "meetups" for mirror humans were spreading like wildfire on social media, with thousands of people eager to meet "the other version of themselves".
Ethan and Mason were dispatched to Berlin on an urgent mission. They were the only pair of mirror humans who had undergone deep contact without experiencing physical exchange, and scientists hoped to find a way to suppress the fusion process by studying them.
The overlapping zone in Berlin had already been placed under military lockdown. Looking out the car window, Ethan witnessed an unbelievable sight: Buildings from 1945 stood side by side with their modern-day replacements, the two architectural styles warping and blending together at the boundaries. The pedestrians on the street were even more surreal—some were half-dressed in modern clothing and half in outfits from the 1940s, like two photographs crudely spliced together.
The investigation team met with the scientists studying an "exchange case" in a temporary lab. The elderly man was named Hans, eighty years old. His mirror human counterpart—or rather, the Hans from the other world—was named Heinrich, a ten-year-old boy who theoretically should have died in the 1945 bombing.
"I can feel him," Hans said in German, the translator converting his words in real time. "His memories are inside my head. The terror I felt on that day in March 1945, when the bombs fell... I remember it all clearly."
The ten-year-old Heinrich sat quietly in a chair, staring at his own hands. His fingers flickered between transparency and solidity.
"We've run every test imaginable," the German scientist said. "Their DNA is starting to converge. Not just becoming similar—rather, expressing two different versions simultaneously. Like different alleles of the same gene being activated at once."
Dr. Zhou asked, "What about their physical state?"
"The law of conservation of mass has been violated. The combined weight of the two of them remains constant, but how that mass is distributed between them keeps changing. At one point, Hans weighed only thirty kilograms while Heinrich weighed fifty. Now, they've stabilized at forty kilograms each."
"What does this mean?" Ethan asked.
The German scientist gave a bitter smile. "It means that our physical laws are breaking down in certain places. Within the overlapping zones, the rules of two different worlds are competing against each other. Whichever side gains the upper hand determines which version of reality prevails."